Expander sealing

[cancsco]

Hi all,
I need some advise on the sealing of a steam expander.
This expander is used in a power generation unit and it runs contiuously. It was running in a fair condition before and now suddenly there was a time when there was a sudden incerase in temperature of incoming steam cos of which the performance has deteriorated. I cannot stop the expander as it has to be running continuously and there is no backup unit for this one. After analyzing the flow rates and pressure buildups I have come to a conclusion that the performance drop is due to the gaps formed inside the expander. From my calculation the gaps cannot be more than 0.002-0.003". Is there any way to put some kind of sealant downstream with the steam and let it fill the gaps.
Operating conditions are
Temperature -250 F
Pressure -250 psi
RPM 3000
Any help in suggesting sealants that can work in the above operating conditions is greatly appreciated

 

[rmw]

You are saying that you want to inject some type of sealant into the steam to fill the gaps of .002-.003" in an expander turning how fast??? I'm thinking a scheme like this will solve your problem, because when whatever material anyone might suggest to do this hits the tight clearances in a machine turning this fast, after the wreck, and the subsequent overhaul, you will have your original clearances restored, and hence, be back to your original performance.

My vote is "not a good idea."

rmw